14 MONTANA EXPERIMENT STATION BULLETIN 457 



In the Bitterroot and Gallatin valleys a heavy second genera- 

 tion moth flight was observed. However, no second generation 

 larvae were reported. 



SPINACH LEAF MINER (Pegomya hyoscyami) 



This insect may be found wherever sugar beets are grown in 

 Montana but generally it is of little economic importance. How- 

 ever, it caused some damage to sugar beet fields in the vicinity of 

 Great Falls and Conrad in 1948. 



SUGAR BEET ROOT MAGGOT (Tetanops aldrichi) 



In the western Montana sugar beet growing area, the sugar 

 beet root maggot causes light damage every year. In the Bitterroot 

 Valley, considerable damage occurred in 1948. Some fields were 

 abandoned because of the heavy infestation. It seems that the 

 populations of this insect have been increasing for the last five 

 years. The poor growing conditions prevailing during the early 

 part of 1948 probably contributed to the damage caused by this 

 insect by lessening the plants ability to recover. 



PEAS 



PEA WEEVIL {Bruchus pisorum) 



The first mention of this pest having been introduced into 

 Montana was in 1912, at which time it was found in seed shipped 

 into the Gallatin Valley. Its occurrence in economically important 

 numbers has been periodic throughout the years from 1912 to the 

 present time. It has been found in the Yellowstone and the Clarks 

 Fork valleys in south-central Montana and in the western part of 

 the state. In general, the populations of the pea weevil in the 

 Bitterroot Valley were lighter in 1947 than in 1948. In some areas 

 of south-central Montana and western Montana populations were 

 sufficiently high to necessitate control measures in both 1947 and 

 1948. To what extent this insect has been able to overwinter under 

 Montana conditions has not yet been established. 



INSECTS INJURIOUS TO GARDEN AND TRUCK CROPS 



CRUCIFERA 



CABBAGE MAGGOT (Hylemya hrassicae) 



The cabbage maggot is distributed throughout Montana and 

 its activities generally result in some damage every year. This 

 insect attacks the roots of all cruciferous plants. No severe out- 

 breaks have been reported in the last two years. However, in years 

 previous to these this pest has been recorded as causing damage in 

 the Bitterroot Valley. 



